ABSTRACT
INTRODUCTION: The summary of product characteristics of vaccines administered intramuscularly, including the vaccine for coronavirus SARS-CoV-2 (COVID-19) and Influenza, warned for risks of bleeding in patients treated with oral anticoagulants. We aimed to estimate the incidence of major bleeding events in this setting and to compare these risks against other vaccination routes. METHODS: This systematic review included all prospective and retrospective studies enrolling anticoagulated patients that received intramuscular vaccination, published until December 2020 in CENTRAL, MEDLINE and EMBASE. The outcomes of interest were major bleeding and haematoma related with vaccination. The incidence of the outcomes was estimated through a random-effects meta-analysis using the Freeman-Turkey transformation. The results are expressed in percentages, with 95%-confidence intervals (95%CI), limited between 0 and 100%. When studies compared intramuscular vaccination vs. other route, the data were compared and pooled using random-effects meta-analysis. Risk ratios (RR) with 95%CI were reported. RESULTS: Overall 16 studies with 642 patients were included. No major bleeding event was reported. The pooled incidence of haematomas following vaccination (mostly against Influenza) in patients treated with oral anticoagulants (mostly warfarin; no data with DOACs / NOACs) was 0.46% (95%CI 0-1.53%). Three studies evaluated the intramuscular vs. subcutaneous route of vaccination. Intramuscular vaccines did not increase the risk of haematoma (RR 0.53, 95%CI 0.10-2.82) compared with subcutaneous route. CONCLUSIONS: Intramuscular vaccination in anticoagulated patients is safe with very low incidence of haematomas and the best available evidence suggests that using the intramuscular route does not increase the risk of haematomas compared with the subcutaneous route.
ABSTRACT
OBJECTIVE: Despite the progression of treatments over decades, heart failure (HF) is a disease with high morbidity, mortality and economic burden. Influenza infection is an important trigger for cardiovascular (CV) events, including HF. Influenza vaccination has been seen to reduce the risk of CV mortality in patients with coronary disease, but the effect in patients with HF is still unclear. Therefore, we conducted a systematic review to evaluate the effect of influenza vaccination in the morbimortality of patients with HF. METHODS: MEDLINE, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Health Technology Assessment and PsycINFO databases (December 2018) were searched for longitudinal studies evaluating influenza vaccination compared with a non-vaccination control group in patients with HF. The risk of bias was assessed according to the ROBINS-I tool. We performed a random-effects meta-analysis to estimate the pooled HRs with 95% CIs, and heterogeneity was evaluated using the I2 statistics. RESULTS: Six cohort studies evaluating 179 158 patients with HF were included in the meta-analysis. Influenza vaccination was associated with a lower risk of all-cause mortality (HR=0.83; 95% CI 0.76 to 0.91; I2=75%). The effect of the influenza vaccination was not statistically significant in a pooled analysis of CV mortality (HR=0.92, 95% CI 0.73 to 1.15; 2 studies) and of all-cause hospitalisations (HR=1.01, 95% CI 0.92 to 1.11; 2 studies). The majority of outcomes in the included studies had a serious risk of bias and almost all evaluated outcomes had very low Grading of Recommendation, Assessment, Development and Evaluation (GRADE) evidence. CONCLUSIONS: Influenza vaccination was associated with a significant decrease in all-cause mortality risk in patients with HF.
